This study was performed to test the production of combustion toxic gases by Pinus rigida specimens treated with various types of methylpiperazinomethyl-bis-phosphonic acid M n + (PIPEABPM n + ) and methylpiperazinomethyl-bis-phosphonic acid (PIPEABP). Three coats of 15 wt% PIPEABPM n + and PIPEABP solutions were applied to plates of Pinus rigida at room temperature. After drying the treated specimens, the production of combustion toxic gases was examined using a cone calorimeter (ISO 5660-1). The specimens treated with PIPEABPM n + showed lower carbon monoxide production (CO p e a k ; 0.0136~0.0178% at 532~678 s) than the PIPEABP plates, except for the specimen treated with PIPEABPFe 3 + . In addition, the peak carbon dioxide production (CO 2 p e a k ) was lower (0.03648~0.3648% at 373~433 s) than that of the PIPEABP-treated plate. Notably, oxygen production was much higher than 15%, which can be fatal to humans. Therefore, the resulting risk could be eliminated. The results indicate that the combustion toxicities were partially decreased due to treatment of the virgin plate with PIPEABPM n + .